Light sources such as light emitting diodes (LEDs) can generate visible or non-visible light (hereinafter, “primary light”) in a specific region of the electromagnetic spectrum, such as in the visible (e.g., blue, red, green, etc.), ultra-violet (UV), near-UV, and/or infrared regions, combinations thereof, and/or light in some other region of the electromagnetic spectrum. The wavelength or wavelength range of the emitted primary light may depend on various parameters, such as but not limited to the material composition of an LED. In any case, the primary light may be light of a first wavelength or wavelength range.
Wavelength converters may be used to construct a lighting device that produces light (hereinafter, “secondary light”) that is of a second wavelength or wavelength range that is different from the first wavelength or wavelength range of primary light incident thereon. Such wavelength converters generally include one or more wavelength conversion materials that function to convert all or a portion of primary light incident thereon to secondary light, e.g., via photoluminescence. The second wavelength/wavelength range may depend on various parameters, such as but not limited to the type and composition of wavelength conversion material in the wavelength converter. Secondary light of a desired wavelength/wavelength range may therefore be attained by proper selection of wavelength conversion material. An LED light source that is combined with a wavelength converter may be understood to be a “wavelength converted LED.”
Quantum dots (QDs) (also referred to as semiconductor nanocrystals) are relatively new materials that have potential use in the lighting industry. Like conventional phosphor particles, some quantum dots have the ability to absorb incident primary light and to emit secondary light in another portion of the electromagnetic spectrum. Many QDs exhibit properties that can be leveraged to create wavelength converters with precisely designed output spectra. Such properties include, for example, a broad absorption spectrum (freedom of the choice of the pump (primary light) wavelength) and emission of secondary light within a narrow-band (25-50 nm) with the peak emission wavelength determined by the material and size of the QDs. The peak emission wavelength of the QDs may therefore be finely tuned, e.g., within few nanometers, by controlling their size and/or composition. QDs can thus enable lighting designers to create wavelength converters that produce secondary light that includes a finely tuned spectrum of emission colors. Quantum dots have therefore been investigated for potential use in the formation of novel wavelength converters for semiconductor devices such as LEDs.
A significant amount of heat may be generated by the conversion of primary light to secondary light by wavelength conversion materials in a wavelength converter, as well as operation of a light source generating the primary light. Inadequate dissipation of heat can cause the temperature of a wavelength converter to increase substantially during the operation of a lighting device, potentially degrading performance of the wavelength conversion material and the lighting device as a whole Accordingly, there is an interest in the development of new approaches to managing the heat in lighting devices such as wavelength converted LEDs.